Class 9, Science, Chapter-2, Lecture-1, Mixture (Notes)
ELEMENT:
The simplest form of matter which cannot be decomposed, by ordinary chemical means, into simpler substances, nor can be formed by combination of other substances is called element.
Classification:
- Metals: Solid (Mercury is the only Liquid metal)
Hard (Exception-Sodium, Potassium)
Good conductors. - Non-Metals: Gaseous or Solid (Bromine is the only Liquid non-metal)
Soft (Exception-Diamond)
Bad conductor (Exception-Graphite)
COMPOUND:
A pure substance formed from two or more elements combined together in definite proportion by weight is called a compound.
Properties of Compounds:
- The constituent elements cannot be separated by physical methods.
- The properties of compounds are different from those of its constituents.
- The constituent elements are present in a fixed proportion by weight.
- Compounds have a fixed melting and boiling point.
- A compound is a homogeneous substance.
- A compound has a definite formula.
- Energy is released or absorbed during formation of compounds.
MIXTURE:
A substance containing two or more elements or compounds in any proportion and the components of which can be separated by simple mechanical methods is called a mixture.
Examples: Air, Gun powder, Steel.
Types of Mixture (On the basis of composition):
- Homogeneous Mixture:
A mixture which has a uniform composition throughout its mass is called homogeneous mixture. - Heterogeneous Mixture:
A mixture which does not have a uniform composition throughout its mass is called heterogeneous mixture.
Properties of Mixture:
- The constituents can be separated by physical methods like filtration, evaporation, sublimation, magnetic separation.
- It retains the properties of its constituents.
- The constituents may be present in any ratio.
- Mixtures do not have fixed melting point or boiling point.
- Mixtures may be homogeneous or heterogeneous.
- Mixtures do not have definite formulae.
- Energy is neither given out nor absorbed during formation of mixtures.
Differences Between:
Mixture |
Compound |
---|---|
No new substance is formed. |
New substance is formed. |
Composition of mixture is variable. |
Composition of compound always remains same. |
Constituents retain their properties. |
Constituents lose their properties. |
Constituents can be separated by physical methods. |
Constituents cannot be separated by physical methods. |
Differences Between:
Element |
Compound |
---|---|
Cannot be split up into two or more different substances. |
Can be split up into two or more different substances |
Made up of atoms of same kind |
Made up of atoms of different kinds. |
Made up of the same substance |
Made up of two or more different substances |